The sisters are together again for a graduation ceremony and party at the sorority house with their parents. They each get a text with a picture of the cross-shaped tire iron (tyre iron, wheel brace, lug wrench ... however you want to call it!) that killed Megan. They assume it is Garrett, the brother of Chugs, being weird. Chugs leaves the party early to meet with her Shrink. He doesn't seem to be home so she wanders around the corridors of the modern office/apartment ... until she finds him tied up in bed from an earlier session. He asks for a sexual favor in return for a few free meds. As Chugs gets ready, there is somebody else in the building.
The Psychiatrist manages to unlock himself just in time to see a dark figure in a hooded graduation cloak peek around the corner -- who unleashes a tire iron with amazing accuracy, from a good distance away, straight through his head. So we're still not sure how strong or tall they are ... is it Megan's skeleton??
Chugs lies down on a table for a rest. The hooded murderer creeps up on her ... and slams a beer bottle fully down her neck until she chokes, then slices her neck.
Meanwhile Jessica is off to meet (her boyfriend) Kyle's dad, and it's clear he doesn't trust her.
Back at the sorority house they get ready for the mad party that night. Carrie Fisher tells them to be good and not trash the house. Taking a pre-party shower, Claire and Jessica talk about Megan, thinking the other stalls to be empty - but another sister overhears everything. As she is about to leave, she is murdered with the tire iron.
Ellie is still busy decorating when she goes down to the scary basement and is frightened by Kyle - before she finds Megan's bloody coat. She screams as usual and races up to tell the others. They still think it's creepy Garrett.
The party is soon is full swing. Cassidy has made her boyfriend Andy swear to her that he is leaving town as it's not safe.
Claire's boyfriend, Mickey, is stalked by the hooded murderer. He ventures into the house. In the upstairs deserted room he steps towards a long mirror, when suddenly he is slashed across the ankles by the killer, and then when he tries to make a run for it ... down a laundry chute ... he is impaled with the tire iron - through a wall.
Ellie finds the body and freaks out. She can't get her words out to the girls. Jessica and Cassidy bravely enter the room to find Mickey's body.
Soon the girls each receive a text with a video clip from Megan's phone shot just after the 'murder' before. Is Megan back from the dead? The text tells them to meet where it happened or the video is going to the cops. They get into a car and race off, but not before they almost hit Megan's younger sister.
At the construction site/mine where Megan died they find Garrett, the brother of Chugs, the unsuspecting murderer, who is still acting weird and freaking out, covered in blood. He comes at them with a sharp object, so Jessica runs him over. No one seems bothered about this one extra little death. The blood is his own from cutting his wrists. They leave him behind.
Cassidy is lowered into the mineshaft to try and find the body ... but it's not there. On the wall, written in blood, are the words "Theta Pi must die!".
The girls return from the road-trip, and the house is deserted. Did the party move on ... or has the killer been busy? The hot-tub is going crazy. Claire wades through the bubbles cautiously to turn off the power ... and doesn't last long before she is the next victim.
In the house Cassidy, Jessica and Ellie, the shy one, each get a text from Chugs - to say she can't make it ... as she's dead. They lock the doors and run upstairs, but not before brave Cass runs out to help Claire - and finds her near the hot tub with the remains of a flare charge in her mouth.
Jessica goes up to her room - to find that Megan's sister was in bed with her boyfriend. The boyfriend has done a runner.
Carrie Fisher returns - with a shotgun. She takes it on herself to defend the house and the girls. In the kitchen she gets off a good number of shots at the intruder ... but is sandwiched behind a heavy table - and the hanging tire iron on the wall behind her, and gives out. Poor Carrie Fisher, why does she keep on going with these B-movies?? The killer next launches a fire bomb at Megan's sister, causing a fire to rage out of control. So we can assume it's not Megan hiding under there.
Jessica's boyfriend, wearing the graduation gown, goes a little psycho and turns on the girls. Jessica and Cass hide in a bathroom - and find Megan's decomposing body hanging up. Kyle breaks through the door and is about to kill Cassidy, when Andy shows up just in time and stabs him in the head to save the day.
Andy then turns around and kills Jessica, stabbing her through the mouth with the same old tire iron.
So then we find out that Andy (the boyfriend of Cassidy, the main heroine) is the hooded graduation-down murderer, and has killed everyone who knew about the 'secret'.
Andy wants to find Ellie to end it. Cassidy plays him, and leads him off in the wrong direction. She then runs to grab the shy one, and they make their way through the house, which is now on fire. All this time no one outside has seemed concerned about the huge fire demolishing a big building on campus. Andy shows up, but is knocked out. He's knocked out a few more times, before he traps Megan's sister in a burning room. The girls return to rescue her. The floor gives way and Cassidy hangs on.
Andy is about to kill her for not trusting him, when Ellie shoots the killer with Carrie Fisher's shotgun. He falls into the flames.
Finally the three remaining girls walk out from the wreckage as the fire crews arrive.
As it ends, we see the next crop of Theta Pi sisters, with Megan's sister among them ... and one of the garden workers looking on menacingly with a sharp weapon has slashed wrists just like Chug's brother who we thought was dead.